1. Technical Field of the Invention
The present invention relates to a continuous vacuum processing apparatus for forming layers on workpieces to continuously produce components such as ceramic oscillators.
2. Description of Related Art
Components such as ceramic oscillators have been commonly produced by a batch-mode electrode layer-forming method which is low in productivity and unfavorable for mass-production.
A film deposition method using continuous vacuum processing has higher productivity, and thus various apparatuses of such kind have been proposed. Among them is a multi-stage differential pressure apparatus disclosed in Japanese Published Unexamined Patent Application 6-88235 (1994), in which a sheet of thin steel is held and conveyed by a plurality of seal rollers for the continuous vacuum processing.
One of conventional continuous vacuum processing apparatuses will be explained referring to FIG. 11. As shown, there are provided a running film 71, a supply reel 72, a take-up reel 73, and guide rolls 74. A vacuum sealing assembly denoted as 75 comprises a casing 76, a seal roll 77, and seal bars 78 to 83. A group of pressure reducing compartments 84 to 88 from the first to fifth stages are formed between the seal roll 77 and the seal bars 78 to 83. The compartments 84 to 88 are decompressed in stages by a vacuum exhausting unit 90 connected thereto by a vacuum conduit 89. Also provided are an evaporation chamber 91, a cooling roll 92, and an evaporation device 93.
The action of the above-described conventional continuous vacuum processing apparatus will now be explained. When the running film 71 is unrolled from the supply reel 72, it passes through the guide roll 74 and the vacuum sealing assembly 75 and is guided into the evaporation chamber 91 for vacuum processing. As the film 71 is wound and runs on the cooling roll 92, it is subjected to evaporation process in the evaporation device 93 before reeled out into the atmosphere. The running film 71 is then guided by the guide roll 74 and taken up by the take-up reel 73.
The above-described conventional apparatus allows the running film to be conveyed at high speed hence contributing to the improvement of the productivity, but creates the following disadvantages when the running film carries a multiplicity of workpieces taped down thereto to be processed.
(1) The thickness of the running film varies depending on either the presence or absence and the size of workpieces on the running film. This increases the gap for sealing and makes the reduction of pressure to a vacuum difficult.
(2) The apparatus comprises a multiple of rollers, making the construction complex, especially in the sealing part.
(3) Hence, the whole apparatus and its vacuum exhaust units will hardly be minimized in the dimensions.